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The process of formulating a problem, finding a solution, and expressing
it.
A programming language like Python that is designed to be easy for
humans to read and write.
A programming language that is designed to be easy for a computer
to run; also called “machine language” or “assembly language”
portability
interpreter
Characters displayed by the interpreter to indicate that it is ready to take input
from the user.
program
An instruction that causes the Python interpreter to display a value on
the screen.
A special symbol that represents a simple computation like addition, multiplication,
or string concatenation.
One of the basic units of data, like a number or string, that a program manipulates.
A category of values. The types we have seen so far are integers (type int), floatingpoint
numbers (type float), and strings (type str).
A type that represents whole numbers.
A type that represents numbers with fractional parts.
A type that represents sequences of characters.
Any one of the languages that people speak that evolved naturally.
Any one of the languages that people have designed for specific purposes,
such as representing mathematical ideas or computer programs; all programming
languages are formal languages.
One of the basic elements of the syntactic structure of a program, analogous to a
word in a natural language.
The rules that govern the structure of a program.
To examine a program and analyze the syntactic structure.
An error in a program.
The process of finding and correcting bugs.
A name that refers to a value.
A statement that assigns a value to a variable.
A graphical representation of a set of variables and the values they refer to.
A reserved word that is used to parse a program; you cannot use keywords like
if, def, and while as variable names.
One of the values on which an operator operates.
A combination of variables, operators, and values that represents a single result.
To simplify an expression by performing the operations in order to yield a single
value.
A section of code that represents a command or action. So far, the statements
we have seen are assignments and print statements.
To run a statement and do what it says.
A way of using the Python interpreter by typing code at the prompt.
A way of using the Python interpreter to read code from a script and run it.
A program stored in a file.
Rules governing the order in which expressions involving multiple
operators and operands are evaluated.
To join two operands end-to-end.
Information in a program that is meant for other programmers (or anyone reading
the source code) and has no effect on the execution of the program.
An error in a program that makes it impossible to parse (and therefore impossible
to interpret).
An error that is detected while the program is running.
The meaning of a program.
An error in a program that makes it do something other than what the
programmer intended.
A named sequence of statements that performs some useful operation. Functions
may or may not take arguments and may or may not produce a result.
A statement that creates a new function, specifying its name, parameters,
and the statements it contains.
A value created by a function definition. The name of the function is a
variable that refers to a function object.
The first line of a function definition.
The sequence of statements inside a function definition.
A name used inside a function to refer to the value passed as an argument.
A statement that runs a function. It consists of the function name followed
by an argument list in parentheses
A value provided to a function when the function is called. This value is assigned
to the corresponding parameter in the function.
A variable defined inside a function. A local variable can only be used
inside its function.
The result of a function. If a function call is used as an expression, the return
value is the value of the expression.
A function that returns a value
A function that always returns None
A special value returned by void functions.
A file that contains a collection of related functions and other definitions.
A statement that reads a module file and creates a module object.
A value created by an import statement that provides access to the values
defined in a module
The syntax for calling a function in another module by specifying the module
name followed by a dot (period) and the function name
Using an expression as part of a larger expression, or a statement as part of
a larger statement
The order statements run in.
A graphical representation of a stack of functions, their variables, and the
values they refer to.
A box in a stack diagram that represents a function call. It contains the local variables
and parameters of the function
A list of the functions that are executing, printed when an exception occurs.
A function that is associated with an object and called using dot notation.
A part of a program that can run repeatedly.
The process of transforming a sequence of statements into a function definition
The process of replacing something unnecessarily specific (like a number)
with something appropriately general (like a variable or parameter).
An argument that includes the name of the parameter as a “keyword”.
A description of how to use a function, including the name and descriptions of
the arguments and return value
The process of modifying a working program to improve function interfaces
and other qualities of the code.
A process for writing programs.
A string that appears at the top of a function definition to document the function’s
interface
A requirement that should be satisfied by the caller before a function starts
A requirement that should be satisfied by the function before it ends.
An operator, denoted //, that divides two numbers and rounds down (toward
negative infinity) to an integer.
An operator, denoted with a percent sign (%), that works on integers
and returns the remainder when one number is divided by another
An expression whose value is either True or False
One of the operators that compares its operands: ==, !=, >, <, >=, and
<=.
One of the operators that combines boolean expressions: and, or, and
not.
Astatement that controls the flow of execution depending on some
condition
The boolean expression in a conditional statement that determines which
branch runs.
A statement that consists of a header and a body. The header ends
with a colon (:). The body is indented relative to the header.
One of the alternative sequences of statements in a conditional statement.
A conditional statement with a series of alternative branches
A conditional statement that appears in one of the branches of another
conditional statement.
A statement that causes a function to end immediately and return to the
caller.
The process of calling the function that is currently executing.
A conditional branch in a recursive function that does not make a recursive call.
A recursion that doesn’t have a base case, or never reaches it. Eventually,
an infinite recursion causes a runtime error.
A variable used to store an intermediate value in a complex calculation
Part of a program that can never run, often because it appears after a return
statement.
A program development plan intended to avoid debugging by
adding and testing only a small amount of code at a time.
Code that is used during program development but is not part of the final
version.
A programming pattern that uses a conditional statement to check for and handle
circumstances that might cause an error.
Assigning a new value to a variable that already exists.
An assignment where the new value of the variable depends on the old.
An assignment that gives an initial value to a variable that will be updated
An update that increases the value of a variable (often by one).
An update that decreases the value of a variable.
Repeated execution of a set of statements using either a recursive function call
or a loop.
A loop in which the terminating condition is never satisfied.
A general process for solving a category of problems.
Something a variable can refer to. For now, you can use “object” and “value”
interchangeably
An ordered collection of values where each value is identified by an integer
index
One of the values in a sequence.
An integer value used to select an item in a sequence, such as a character in a string.
In Python indices start from 0.
A part of a string specified by a range of indices.
A string with no characters and length 0, represented by two quotation
marks.
The property of a sequence whose items cannot be changed.
To iterate through the items in a sequence, performing a similar operation on
each.
A pattern of traversal that stops when it finds what it is looking for.
A variable used to count something, usually initialized to zero and then incremented.
A statement that calls a method.
A function or method argument that is not required.
A value that represents an open file.
A way of solving a problem by expressing it
as an instance of a previously solved problem.
A test case that is atypical or non-obvious (and less likely to be handled correctly
A sequence of values.
One of the values in a list (or other sequence), also called items.
A list that is an element of another list.
A variable used in a loop to add up or accumulate a result.
A statement that updates the value of a variable using an operator
like +=.
A processing pattern that traverses a sequence and accumulates the elements into
a single result.
A processing pattern that traverses a sequence and performs an operation on each
element.
A processing pattern that traverses a list and selects the elements that satisfy some
criterion.
Something a variable can refer to. An object has a type and a value
Having the same value.
Being the same object (which implies equivalence).
The association between a variable and its value.
A circumstance where two or more variables refer to the same object.
A character or string used to indicate where a string should be split.
A relationship in which each element of one set corresponds to an element of
another set
A mapping from keys to their corresponding values.
The representation of the mapping from a key to a value
In a dictionary, another name for a key-value pair.
An object that appears in a dictionary as the first part of a key-value pair.
An object that appears in a dictionary as the second part of a key-value pair. This is
more specific than our previous use of the word “value”.
A way of performing a computation.
The algorithm used to implement Python dictionaries.
A function used by a hashtable to compute the location for a key.
Atype that has a hash function. Immutable types like integers, floats and strings
are hashable; mutable types like lists and dictionaries are not
A dictionary operation that takes a key and finds the corresponding value.
A dictionary operation that takes a value and finds one or more keys that
map to it.
A statement that (deliberately) raises an exception.
A list (or other sequence) with a single element.
A diagram that shows every frame created during the execution of a program,
with an arrow from each caller to each callee.
A computed value stored to avoid unnecessary future computation
A variable defined outside a function. Global variables can be accessed
from any function.
A statement that declares a variable name global.
boolean variable used to indicate whether a condition is true.
A statement like global that tells the interpreter something about a variable.
An immutable sequence of elements.
An assignment with a sequence on the right side and a tuple of variables
on the left. The right side is evaluated and then its elements are assigned to the
variables on the left.
The operation of assembling a variable-length argument tuple.
The operation of treating a sequence as a list of arguments.
The result of calling a built-in function zip; an object that iterates through a
sequence of tuples.
An object that can iterate through a sequence, but which does not provide list
operators and methods
A collection of related values, often organized in lists, dictionaries, tuples,
etc.
An error caused because a value has the wrong shape; that is, the wrong type
or size
Pertaining to a program that does the same thing each time it runs, given
the same inputs.
Pertaining to a sequence of numbers that appears to be random, but is
generated by a deterministic program.
The value given to an optional parameter if no argument is provided.
To replace a default value with an argument.
The process of choosing between data structures by implementing alternatives
and testing them on a sample of the possible inputs
Debugging by explaining your problem to an inanimate object
such as a rubber duck. Articulating the problem can help you solve it, even if the
rubber duck doesn’t know Python.
Pertaining to a program that runs indefinitely and keeps at least some of its
data in permanent storage.
An operator, %, that takes a format string and a tuple and generates a
string that includes the elements of the tuple formatted as specified by the format
string.
A string, used with the format operator, that contains format sequences.
A sequence of characters in a format string, like %d, that specifies how a
value should be formatted.
A sequence of characters stored in permanent storage like a hard drive.
A named collection of files, also called a folder.
A string that identifies a file.
A path that starts from the current directory.
A path that starts from the topmost directory in the file system.
To prevent an exception from terminating a program using the try and except statements.
: A file whose contents are organized like a dictionary with keys that correspond
to values.
An object similar to a string.
A program that allows users to type commands and then executes them by starting
other programs.
An object that represents a running program, allowing a Python program to
run commands and read the results.
A programmer-defined type. A class definition creates a new class object.
: An object that contains information about a programmer-defined type. The
class object can be used to create instances of the type.
An object that belongs to a class.
To create a new object.
: One of the named values associated with an object.
An object that is stored as an attribute of another object.
To copy the contents of an object, including any references to embedded objects; implemented by the copy function in the copy module.
To copy the contents of an object as well as any embedded objects, and any
objects embedded in them, and so on; implemented by the deepcopy function in the
copy module.
A diagram that shows objects, their attributes, and the values of the attributes
A development plan that involves writing a rough draft of a program,
testing, and correcting errors as they are found.
A development plan that involves high-level insight into the
problem and more planning than incremental development or prototype development.
A function that does not modify any of the objects it receives as arguments.
Most pure functions are fruitful.
A function that changes one or more of the objects it receives as arguments. Most
modifiers are void; that is, they return None.
A style of program design in which the majority of functions
are pure.
A condition that should always be true during the execution of a program.
A statement that check a condition and raises an exception if it fails
A language that provides features, such as programmer defined
types and methods, that facilitate object-oriented programming.
A style of programming in which data and the operations
that manipulate it are organized into classes and methods.
A function that is defined inside a class definition and is invoked on instances of
that class.
The object a method is invoked on.
An argument that does not include a parameter name, so it is not a
keyword argument.
Changing the behavior of an operator like + so it works with a
programmer-defined type.
