@property<EOL><INDENT>@memoize<EOL>def s1p(self):<DEDENT>
M_P = <NUM_LIT>         <EOL>f = lambda parent, daugther: -parent + daugther + M_P<EOL>return self.derived('<STR_LIT>', (-<NUM_LIT:1>, <NUM_LIT:0>), f)<EOL>
Return 1 proton separation energy