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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_regulate_amount(stmt):
 """Assemble RegulateAmount statements into text."""

    obj_str = _assemble_agent_str(stmt.obj)
    if stmt.subj is not None:
        subj_str = _assemble_agent_str(stmt.subj)
        if isinstance(stmt, ist.IncreaseAmount):
            rel_str = ' increases the amount of '
        elif isinstance(stmt, ist.DecreaseAmount):
            rel_str = ' decreases the amount of '
        stmt_str = subj_str + rel_str + obj_str
    else:
        if isinstance(stmt, ist.IncreaseAmount):
            stmt_str = obj_str + ' is produced'
        elif isinstance(stmt, ist.DecreaseAmount):
            stmt_str = obj_str + ' is degraded'
    return _make_sentence(stmt_str)