docstr: Return *True* if the block has nested namespaces.
          
code: def has_children(self):
      """Return *True* if the block has nested namespaces."""
      return bool(self._table.children)
  
imports: import _symtable
  from _symtable import USE, DEF_GLOBAL, DEF_NONLOCAL, DEF_LOCAL, DEF_PARAM, DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE, LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL
  import weakref
label_desc: Use image node_id 9 for calling the SymbolTable obj's underlying member method code with example usage: obj.has_children() and returns: bool