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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def str2long(s):
 """Convert a string to a long integer."""

    if type(s) not in (types.StringType, types.UnicodeType):
        raise ValueError('the input must be a string')

    l = 0
    for i in s:
        l <<= 8
        l |= ord(i)

    return l