Usage: BIND <key> SWITCH_CHANNELS
  Changes the current channel for the current window.  This will
  only switch to a channel not currently directed to another
  window.  That is, if you are on three channels, #Foo, #Bar,
  and #Cheese, and #Foo and #Bar are currently directed to two
  windows but #Cheese isn't, then SWITCH_CHANNELS will only
  toggle between #Cheese and either #Foo or #Bar (depending upon
  which window this is done in)
