old_contents: #!/usr/bin/env python
  # coding: utf-8
  
  from .base import Column
  
  class SequenceColumn(Column):
      def __init__(self, field, headers, **kwargs):
          self.headers = headers
          self.kwargs = kwargs
          super(SequenceColumn, self).__init__(field, **kwargs)
  
      @property
      def columns(self):
          return [self.get_column(key) for key in range(self.__len__())]
  
      def __len__(self):
          return len(self.headers)
  
      def __getitem__(self, key):
          return self.columns[key]
  
      def __setitem__(self, key, value):
          self.columns[key] = value
  
      def get_column(self, key):
          return Column(field=self.get_field(key),
                        header=self.get_header(key),
                        **self.kwargs)
  
      def get_field(self, key):
          return ".".join([self.field, str(key)])
  
      def get_header(self, key):
          return self.headers[key]
  
new_contents: #!/usr/bin/env python
  # coding: utf-8
  
  from .base import Column
  
  class SequenceColumn(Column):
      def __init__(self, field, headers, **kwargs):
          self.headers = headers
          self.kwargs = kwargs
          super(SequenceColumn, self).__init__(field, **kwargs)
  
      @property
      def columns(self):
          return [self.get_column(key) for key in range(self.__len__())]
  
      def __len__(self):
          return len(self.headers)
  
      def __getitem__(self, key):
          return self.columns[key]
  
      def __setitem__(self, key, value):
          self.columns[key] = value
  
      def get_column(self, key):
          return Column(field=self.get_field(key),
                        header=self.get_header(key),
                        **self.kwargs)
  
      def get_field(self, key):
          if self.field:
              return ".".join([self.field, str(key)])
          else:
              return None
  
      def get_header(self, key):
          return self.headers[key]
  
subject: Fix bug about get_field in sequencecolumn