def convert_relational(relational):
rel = relational.rel_op<EOL>if rel in ['<STR_LIT>', '<STR_LIT>', '<STR_LIT:>>']:<EOL><INDENT>return relational.lhs-relational.rhs<EOL><DEDENT>elif rel in ['<STR_LIT>', '<STR_LIT:<>']:<EOL><INDENT>return relational.rhs-relational.lhs<EOL><DEDENT>else:<EOL><INDENT>raise Exception("<STR_LIT>"<EOL>"<STR_LIT>")<EOL><DEDENT>
Convert all inequalities to >=0 form.