''' Purpose: better experience functional development

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'''

# function signum() here
    ''' Function parameter x is a numeric value. The function does not print
        any output. The function returns integer -1, 0, or 1 depending
        respectively whether x is negative, zero, or positive.
    '''

# function mid() here
    ''' If the length of s is odd, the function returns the middle character
        of s; otherwise, the function returns the two middle characters of s.
    '''