code: def doi_uri_to_doi(value):
      "Strip the uri schema from the start of DOI URL strings"
      if value is None:
          return value
      replace_values = ['http://dx.doi.org/', 'https://dx.doi.org/',
                        'http://doi.org/', 'https://doi.org/']
      for replace_value in replace_values:
          value = value.replace(replace_value, '')
      return valuf doi_uri_to_doi(value):
      "Strip the uri schema from the start of DOI URL strings"
      if value is None:
          return value
      replace_values = ['http://dx.doi.org/', 'https://dx.doi.org/',
                        'http://doi.org/', 'https://doi.org/']
      for replace_value in replace_values:
          value = value.replace(replace_value, '')
      return value
docs: Strip the uri schema from the start of DOI URL strings