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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 _assemble_gef(stmt):
 """Assemble Gef statements into text."""

    subj_str = _assemble_agent_str(stmt.gef)
    obj_str = _assemble_agent_str(stmt.ras)
    stmt_str = subj_str + ' is a GEF for ' + obj_str
    return _make_sentence(stmt_str)