Double dispatch methods to support vctrs::vec_ptype2().

## Usage

# S3 method for hms
vec_ptype2(x, y, ..., x_arg = "", y_arg = "")

## Arguments

x, y

Vector types.

...

These dots are for future extensions and must be empty.

x_arg, y_arg

Argument names for x and y. These are used in error messages to inform the user about the locations of incompatible types (see stop_incompatible_type()).