code: def create_for_block(
              cls, i=None, name=None, cname=None, version=None, **kwargs):
          
  
          if cname is None:
              cname = name or 'values_block_{idx}'.format(idx=i)
          if name is None:
              name = cname
  
          # prior to 0.10.1, we named values blocks like: values_block_0 an the
          # name values_0
          try:
              if version[0] == 0 and version[1] <= 10 and version[2] == 0:
                  m = re.search(r"values_block_(\d+)", name)
                  if m:
                      name = "values_{group}".format(group=m.groups()[0])
          except IndexError:
              pass
  
          return cls(name=name, cname=cname, **kwargs)
docs: return a new datacol with the block i