Environments are first class objects in STk. The following primitives are defined on environments.
#entry145# #entry153# #entry158# #entry164# #entry172# #entry182# #entry193#
#entry153# #entry158# #entry164# #entry172# #entry182# #entry193#
#entry158# #entry164# #entry172# #entry182# #entry193#
#entry164# #entry172# #entry182# #entry193#
#entry172# #entry182# #entry193#
#entry182# #entry193#
#entry193#