When people need to serialize in a format that differentiates string concatenation from addition, they can use the new `concat` function in an expression. But I don't think we need to throw if people use `+` with strings.
When people need to serialize in a format that differentiates string concatenation from addition, they can use the new `concat` function in an expression. But I don't think we need to throw if people use `+` with strings.