op_add = '+'
op_sub = '-'
op_mul = '*'
op_div = '/'
op_eq = '='
op_neq = '!='
op_imp = '=>'
op_matching = '\u22b3'  # (contains)
op_consistency = '~'
op_precision = '\u2291'  # (square image of or equal to)
op_leq = '\u2264'  # less-than or equal to
op_lt = '<'
op_gt = '>'
op_mod = '%'
