code: def ensure_ring(geom, values=None):
      """Ensure the (multi-)geometry forms a ring.
  
      Checks the start- and end-point of each geometry to ensure they
      form a ring, if not the start point is inserted at the end point.
      If a values array is provided (which must match the geometry in
      length) then the insertion will occur on the values instead,
      ensuring that they will match the ring geometry.
  
      Args:
          geom: 2-D array of geometry coordinates
          values: Optional array of values
  
      Returns:
          Array where values have been inserted and ring closing indexes
      """
      if values is None:
          values = geom
  
      breaks = np.where(np.isnan(geom.astype("float")).sum(axis=1))[0]
      starts = [0] + list(breaks + 1)
      ends = list(breaks - 1) + [len(geom) - 1]
      zipped = zip(geom[starts], geom[ends], ends, values[starts])
      unpacked = tuple(
          zip(*[(v, i + 1) for s, e, i, v in zipped if (s != e).any()])
      )
      if not unpacked:
          return values
      inserts, inds = unpacked
      return np.insert(values, list(inds), list(inserts), axis=0)
  
imports: import numpy
  from ..None import util
  from ..element import Element
  from ..ndmapping import NdMapping, item_check, sorted_context
  from .dictionary import DictInterface
  from .interface import DataError, Interface
label_desc: Use image node_id 1 for calling a global function with example usage: ensure_ring(geom, values) and returns: np, values