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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 _is_protein(pe):
 """Return True if the element is a protein"""

    val = isinstance(pe, _bp('Protein')) or \
            isinstance(pe, _bpimpl('Protein')) or \
            isinstance(pe, _bp('ProteinReference')) or \
            isinstance(pe, _bpimpl('ProteinReference'))
    return val