
abs.erl:16:5: The pattern 
          'true' can never match the type 
          'false'
abs.erl:27:5: The pattern 
          'true' can never match the type 
          'false'
abs.erl:37:5: The pattern 
          'true' can never match the type 
          'false'
abs.erl:49:5: The pattern 
          'true' can never match the type 
          'false'
