print (VarExpr _ vd) = print vd
print (Op2Expr _ e1 o e2) = ["(":print e1] ++ [" ",case o of
BiPlus = "+"; BiMinus = "-"; BiTimes = "*"; BiDivide = "/"
print (VarExpr _ vd) = print vd
print (Op2Expr _ e1 o e2) = ["(":print e1] ++ [" ",case o of
BiPlus = "+"; BiMinus = "-"; BiTimes = "*"; BiDivide = "/"