Python -- filter，map

Type:    builtin_function_or_method
Base Class:  <type 'builtin_function_or_method'>
String Form:  <built-in function map>
Namespace:  Python builtin
Docstring:
        map(function, sequence[, sequence, ...]) -> list
        
        Return a list of the results of applying the function to the items of
        the argument sequence(s).    If more than one sequence is given, the
        function is called with an argument list consisting of the corresponding
        item of each sequence, substituting None for missing values when not all
        sequences have the same length.    If the function is None, return a list of
        the items of the sequence (or a list of tuples if more than one sequence).

Type:    builtin_function_or_method
Base Class:  <type 'builtin_function_or_method'>
String Form:  <built-in function reduce>
Namespace:  Python builtin
Docstring:
        reduce(function, sequence[, initial]) -> value
        
        Apply a function of two arguments cumulatively to the items of a sequence,
        from left to right, so as to reduce the sequence to a single value.
        For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates
        ((((1+2)+3)+4)+5).    If initial is present, it is placed before the items
        of the sequence in the calculation, and serves as a default when the
        sequence is empty.