parameters: (self, first, second)
docstring: Adds the constraint that 'first' should precede 'second'.
docstring_summary: Adds the constraint that 'first' should precede 'second'.
docstring_tokens: Adds the constraint that first should precede second .
function: def add_pair (self, first, second):
          """ Adds the constraint that 'first' should precede 'second'.
          """
          self.constraints_.append ((first, second))
function_tokens: def add_pair ( self , first , second ) : self . constraints_ . append ( ( first , second ) )