Proof of proveit.physics.quantum.algebra.qmult_pulling_scalar_out_front theorem

import proveit
theory = proveit.Theory() # the theorem's theory

%proving qmult_pulling_scalar_out_front

With these allowed/disallowed theorem/theory presumptions (e.g., to avoid circular dependencies), we begin our proof of
qmult_pulling_scalar_out_front:
(see dependencies)