@property<EOL><INDENT>def branchScale(self):<DEDENT>
bs = -(self.prx * scipy.diagonal(self.Prxy, axis1=<NUM_LIT:1>, axis2=<NUM_LIT:2>)<EOL>).sum() * self.mu / float(self.nsites)<EOL>assert bs > <NUM_LIT:0><EOL>return bs<EOL>
See docs for `Model` abstract base class.