Setting flag in macro

[silverscythe69]

Is there any way to set a "variable" in a macro?
Explanation: I am looking to set a variable to a value in order to direct the course of a loop.
Example:

if variable == 'a'
  put cut logs into pack animal a
  set variable to 'b'
else
  put cut logs into pack animal b
  set variable to 'a'
endif