System.Linq.Expressions.Expression.GetMethodBasedBinaryOperator C# (CSharp) Method

        private static BinaryExpression GetMethodBasedBinaryOperator(ExpressionType binaryType, Expression left, Expression right, MethodInfo method, bool liftToNull)
        {
            System.Diagnostics.Debug.Assert(method != null);
            ValidateOperator(method);
            ParameterInfo[] pms = method.GetParametersCached();
            if (pms.Length != 2)
                throw Error.IncorrectNumberOfMethodCallArguments(method, nameof(method));
            if (ParameterIsAssignable(pms[0], left.Type) && ParameterIsAssignable(pms[1], right.Type))
            {
                ValidateParamswithOperandsOrThrow(pms[0].ParameterType, left.Type, binaryType, method.Name);
                ValidateParamswithOperandsOrThrow(pms[1].ParameterType, right.Type, binaryType, method.Name);
                return new MethodBinaryExpression(binaryType, left, right, method.ReturnType, method);
            }
            // check for lifted call
            if (left.Type.IsNullableType() && right.Type.IsNullableType() &&
                ParameterIsAssignable(pms[0], left.Type.GetNonNullableType()) &&
                ParameterIsAssignable(pms[1], right.Type.GetNonNullableType()) &&
                method.ReturnType.GetTypeInfo().IsValueType && !method.ReturnType.IsNullableType())
            {
                if (method.ReturnType != typeof(bool) || liftToNull)
                {
                    return new MethodBinaryExpression(binaryType, left, right, method.ReturnType.GetNullableType(), method);
                }
                else
                {
                    return new MethodBinaryExpression(binaryType, left, right, typeof(bool), method);
                }
            }
            throw Error.OperandTypesDoNotMatchParameters(binaryType, method.Name);
        }