parameters: (cmd, failure_message, **kwargs)
docstring: Call an external program in a subprocess if it exists.
  
      Returns True.
  
      If it does not exist, write a failure message and return False
      without raising an exception
docstring_summary: Call an external program in a subprocess if it exists.
docstring_tokens: Call an external program in a subprocess if it exists .
function: def call_if_exists(cmd, failure_message, **kwargs):
      """
      Call an external program in a subprocess if it exists.
  
      Returns True.
  
      If it does not exist, write a failure message and return False
      without raising an exception
      """
      try:
          call(cmd, **kwargs)
          return True
      except OSError as e:
          if e.errno == errno.ENOENT:
              write(failure_message)
              return False
          else:
              raise
function_tokens: def call_if_exists ( cmd , failure_message , * * kwargs ) : try : call ( cmd , * * kwargs ) return True except OSError as e : if e . errno == errno . ENOENT : write ( failure_message ) return False else : raise