code: def create_column_by_example(self, name, value):
          
          type_ = self.db.types.guess(value)
          self.create_column(name, type_)
docs: Explicitly create a new column ``name`` with a type that is appropriate
          to store the given example ``value``.  The type is guessed in the same
          way as for the insert method with ``ensure=True``.
          ::
  
              table.create_column_by_example('length', 4.2)
  
          If a column of the same name already exists, no action is taken, even
          if it is not of the type we would have created.