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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 encode_int(v):
 """encodes an integer into serialization"""

    if not is_numeric(v) or v < 0 or v >= TT256:
        raise Exception("Integer invalid or out of range: %r" % v)
    return int_to_big_endian(v)