Composite basis set

I am having hard times with the definition of a ‘composite’ basis set within the PyAPI. In other words, in psi4 is possible to mix the basis sets simply
basis {
assign DZ
assign C 3-21G
assign H1 sto-3g
assign C1 sto-3g
What is the equivalent syntax in the case of the Psi4 PyAPI? Alternatively, would it be possible to use to achieve this goal?
Thanks in advance

Solved in
Custom defined basis set