Clarify symbolic type syntax
Clarify symbolic type syntax

cpcloud/datashape,quantopian/datashape,ContinuumIO/datashape,quantopian/datashape,llllllllll/datashape,blaze/datashape,ContinuumIO/datashape,llllllllll/datashape,cpcloud/datashape,blaze/datashape,cowlicks/datashape,cowlicks/datashape