Glossary 5

fruitful function: A function that yields a return value.

return value: The value provided as the result of a function call.

temporary variable: A variable used to store an intermediate value in a complex calculation.

dead code: Part of a program that can never be executed, often because it appears after a return statement.

None: A special Python value returned by functions that have no return statement, or a return statement without an argument.

incremental development: A program development plan intended to avoid debugging by adding and testing only a small amount of code at a time.

scaffolding: Code that is used during program development but is not part of the final version.

guardian: A condition that checks for and handles circumstances that might cause an error.

Glossary 6

multiple assignment: Making more than one assignment to the same variable during the execution of a program.

iteration: Repeated execution of a set of statements using either a recursive function call or a loop.

loop: A statement or group of statements that execute repeatedly until a terminating condition is satisfied.

infinite loop: A loop in which the terminating condition is never satisfied.

body: The statements inside a loop.

loop variable: A variable used as part of the terminating condition of a loop.

tab: A special character that causes the cursor to move to the next tab stop on the current line.

newline: A special character that causes the cursor to move to the beginning of the next line.

cursor: An invisible marker that keeps track of where the next character will be printed.

escape sequence: An escape character (\) followed by one or more printable characters used to designate a nonprintable character.

encapsulate: To divide a large complex program into components (like functions) and isolate the components from each other (by using local variables, for example).

generalize: To replace something unnecessarily specific (like a constant value)

with something appropriately general (like a variable or parameter). Generalization makes code more versatile, more likely to be reused, and sometimes even easier to write.

development plan: A process for developing a program. In this chapter, we demonstrated a style of development based on developing code to do simple, specific things and then encapsulating and generalizing.

Glossary 7

compound data type: A data type in which the values are made up of components, or elements, that are themselves values.

traverse: To iterate through the elements of a set, performing a similar operation on each.

index: A variable or value used to select a member of an ordered set, such as a character from a string.

slice: A part of a string specified by a range of indices.

mutable: A compound data types whose elements can be assigned new values.

counter: A variable used to count something, usually initialized to zero and then incremented.

increment: To increase the value of a variable by one.

decrement: To decrease the value of a variable by one.

whitespace: Any of the characters that move the cursor without printing visible characters. The constant string.whitespace contains all the whitespace characters.