class_docstr: A `Composable` object made of a sequence of `!Composable`.
  
  The object is usually created using `!Composable` operators and methods.
  However it is possible to create a `!Composed` directly specifying a
  sequence of `!Composable` as arguments.
  
  Example::
  
      >>> comp = sql.Composed(
      ...     [sql.SQL("insert into "), sql.Identifier("table")])
      >>> print(comp.as_string(conn))
      insert into "table"
  
  `!Composed` objects are iterable (so they can be used in `SQL.join` for
  instance).
code: def __init__(self, seq):
      wrapped = []
      for i in seq:
          if not isinstance(i, Composable):
              raise TypeError(
                  f"Composed elements must be Composable, got {i!r} instead"
              )
          wrapped.append(i)
  
      super().__init__(wrapped)
  
imports: import string
  from psycopg2 import extensions
label_desc: Use image node_id 1 to create a new Composed object from inherited base classes: Composable with example: obj = Composed(seq)