colon character common usage mistakes special case rules - - terminating timing comprehension variables comprehensions (see also list comprehensionsdictionary - - iterables versus - quiz questions and answers set - syntax summary - concatenating lists strings tuples virtual concatenation conflict resolutiondiamond inheritance trees - constants constructors class gotchas coding customizing - __init__ method and operator overloading and superclass __contains__ method - __context__ attribute context managers about - closing files and server connections decimals files implementing multiple - version considerations - contextlib module continuation lines in statements continue statement control flows exceptions and nesting control languages control-flow statements conversions case index for encodings fraction hexoctalbinary notation - integer mixed types storing objects in files - string - string types to converter tuple - to converter copy module core data types (see built-in object typescoupling component functions modules super built-in function - cpickle module cpython system about timeit module and - csv file format csv module curly braces } currency symbols - current working directory (cwd) cwd (current working directory) cx_freeze tool cyclesrecursive calls and cyclic data structures cyclic references cygwin system cython system data attributes data structures about arbitrary - built-in object types and cyclic dictionaries and empty data types (see object typesdatabase programming