''' Purpose: better experience functional development

    Buddies (if any):
'''

# helpful named strings

PUNCTUATION = '''!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~'''
WHITE_SPACE = ' \t\n\r\v\f'
EXTRANEOUS  = PUNCTUATION + WHITE_SPACE

def to_lower( strings ) :
    ''' Returns a new list whose elements are lower case versions of
        those in strings
    '''

    pass

def unique( strings ) :
    ''' Returns a new version of strings without any duplicate values
    '''

    pass


def cleanup( strings ) :
    ''' Returns a new version of strings where the corresponding
        elements have leading and trailing extraneous characters
        (punctuation or whitespace) removed
    '''

    pass

def canonical( strings ) :
    ''' Returns a new version of strings without duplicate values
        where the corresponding elements have leading and trailing
        extraneous characters (punctuation or whitespace) removed
        and are in lowercase
    '''

    pass