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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 _var_uint64_byte_size_no_tag(uint64):
 """Returns the bytes required to serialize a single varint. uint64 must be unsigned. """

    if uint64 > UINT64_MAX:
        raise errors.EncodeError('Value out of range: %d' % uint64)
    bytes = 1
    while uint64 > 0x7f:
        bytes += 1
        uint64 >>= 7
    return bytes