code: def write(self, data, dst, label=None, mode='wb'):
      
      dst = self._normalize(dst)
      self._tag(dst, label)
      self._ensure_parent(dst)
      with open(os.path.join(self.chroot, dst), mode) as wp:
        wp.write(data)
docs: Write data to ``chroot/dst`` with optional label.
  
      Has similar exceptional cases as ``Chroot.copy``