Appendix A. Glossary 22 Installing Python Modules, Release 3.9.5 def remove_gray_shades ( colors:list[tuple[int,int,int]])->list[tuple[int,int,int]]: pass Color =tuple[int,int,int] def remove_gray_shades (colors:list[Color])->list[Color]: pass could be made more readable like this: When annotating a variable or a class attribute, assignment is optional: Variable annotations are usually used for type hints : for example this variable is expected to take$_{int}$ values: Variable annotation syntax is explained in section annassign. See function annotation , PEP 484 and PEP 526 , which describe this functionality. Zen of Python Listing of Python design principles and philosophies that are helpful in understanding and using the language. The listing can be found by typing “$_{import this}$ ” at the interactive prompt. virtual machine A computer defined entirely in software. Python’s virtual machine executes the bytecode emitted by the bytecode compiler. virtual environment A cooperatively isolated runtime environment that allows Python users and applications to install and upgrade Python distribution packages without interfering with the behaviour of other Python appli- cations running on the same system. See also$_{venv}$ . variable annotation An annotation of a variable or a class attribute. universal newlines A manner of interpreting text streams in which all of the following are recognized as ending a line: the Unix end-of-line convention '
' , the Windows convention '\r
' , and the old Macintosh convention$_{'\r'}$ . See PEP 278 and PEP 3116 , as well as$_{bytes.splitlines()}$ for an additional use. type hint An annotation that specifies the expected type for a variable, a class attribute, or a function parameter or return value. Type hints are optional and are not enforced by Python but they are useful to static type analysis tools, and aid IDEs with code completion and refactoring. Type hints of global variables, class attributes, and functions, but not local variables, can be accessed using typing.get_type_hints() . See typing and PEP 484 , which describe this functionality. See$_{typing}$and PEP 484 , which describe this functionality. count:int =0 classC : field:'annotation'