A provider series for one instrument. An absent field is the provider's
default for it, which is itself an identity: {} asks for exactly what a
request without a variant always got, and { session: 'regular' } asks for
regular hours explicitly, whatever the provider's default is.
A provider series for one instrument. An absent field is the provider's default for it, which is itself an identity:
{}asks for exactly what a request without a variant always got, and{ session: 'regular' }asks for regular hours explicitly, whatever the provider's default is.