DOC/TEST: Add doctest and docs for coerce kwargs.
DOC/TEST: Add doctest and docs for coerce kwargs.

nborggren/zipline,grundgruen/zipline,alphaBenj/zipline,florentchandelier/zipline,magne-max/zipline-ja,nborggren/zipline,umuzungu/zipline,bartosh/zipline,Scapogo/zipline,quantopian/zipline,humdings/zipline,quantopian/zipline,Scapogo/zipline,bartosh/zipline,wilsonkichoi/zipline,enigmampc/catalyst,alphaBenj/zipline,umuzungu/zipline,enigmampc/catalyst,magne-max/zipline-ja,florentchandelier/zipline,humdings/zipline,wilsonkichoi/zipline,grundgruen/zipline