You need to call this function if you would like to define a type for a
The name of the type.
A member type can be a user defined type. All the type names are case
sensitive. Built in type names should be provided in lowercase.
The member name of member1_type.
This function takes 2n+1 arguments, where n is the number of members the
type has. After that is the type of the member followed by the members
name (in pairs).
TRUE on success or
FALSE on failure.
This function is
EXPERIMENTAL. The behaviour of this function, the
name of this function, and anything else documented about this
function may change without notice in a future release of PHP.
Use this function at your own risk.