code: def normalize_operations(self, operations):
          
          normalized = OrderedDict()
  
          for operation in operations:
              op_key = (operation.sql_type, operation.obj_name)
  
              # do we already have an operation for this object?
              if op_key in normalized:
                  if self.verbosity >= 2:
                      self.stdout.write(" < %s" % normalized[op_key])
  
                  del normalized[op_key]
  
              # don't add DROP operations for objects not previously created
              if operation.is_create:
                  normalized[op_key] = operation
              elif self.verbosity >= 2:
                  self.stdout.write(" < %s" % operation)
  
          return normalized.values()
docs: Removes redundant SQL operations - e.g. a CREATE X followed by a DROP X