import re
 
def remove_all(sub, s):
    """
>>> remove_all('an', 'banana')
'ba'
>>> remove_all('cyc', 'bicycle')
'bile'
>>> remove_all('iss', 'Mississippi')
'Mippi'
"""
 
    return re.sub(re.escape(sub), '', s)
 
 
if __name__ == '__main__':
    import doctest
    doctest.testmod()

def remove_all(sub, s):
    """
>>> remove_all('an', 'banana')
'ba'
>>> remove_all('cyc', 'bicycle')
'bile'
>>> remove_all('iss', 'Mississippi')
'Mippi'
"""
    return s.replace(sub, '')
 
if __name__ == '__main__':
    import doctest
    doctest.testmod()

def remove( s, rem ):
    newS = ""
    i = 0
    while i < len( s ):
        if s[ i : i + len( rem ) ] == rem:
            i += len( rem )
        else:
            newS += s[ i ]
            i += 1
    print newS
 
s = "Mississippi"; r = "iss"
remove( s, r )

def remove(sub, s):
    # replace first sub with empty string
    return s.replace(sub, "", 1)
 
# test
print( remove('an', 'banana') )        # --> bana
print( remove('iss', 'Mississippi') )  # --> Missippi

def remove_all(sub, s):
    # replace all sub with empty string
    return s.replace(sub, "", -1)
 
# test
print( remove_all('an', 'banana') )        # --> ba
print( remove_all('iss', 'Mississippi') )  # --> Mippi