class_docstr: Credential to access git-credential
      
class_docstr_tok: ["Credential","to","access","git-credential"]
code: def _get_field_value(self, field):
      from datalad import cfg as dlcfg
  
      cfg = self.ds.config if self.ds else dlcfg
      cfg.reload()
      from_cfg = cfg.get(
          "datalad.credential.{name}.{field}".format(
              name=self.name, field=field.replace("_", "-")
          )
      )
  
      if from_cfg:
          # config takes precedence
          return from_cfg
  
      # Note:
      # In opposition to the keyring approach of other `Credential`s,
      # we don't query for single values, but for an entire "description".
      # Currently required methods have to return single values, though.
      # Hence, calls to `git credential fill` could be optimised. Not easy to
      # assess when exactly this class can know whether it's context is yet to
      # be completed, though, so that another `fill` would actually yield
      # something different than before.
  
      self._git_cred.fill()
      git_field = self._FIELDS_GIT[
          field
      ]  # translate to git-credential terms
      if git_field in self._git_cred and self._git_cred[git_field]:
          return self._git_cred[git_field]
  
      # we got nothing
      return
  
imports: import time
  from ..support.exceptions import AccessDeniedError, CapturedException
  from ..support.keyring_ import keyring
  from ..ui import ui
  from ..utils import auto_repr
  from ..support.network import iso8601_to_epoch
  from datalad import cfg
  from datalad.config import anything2bool
  from datalad.distribution.dataset import Dataset
  from datalad.local.gitcredential import GitCredentialInterface
  from logging import getLogger
label_desc: Use image node_id 2 for calling the GitCredential obj's underlying member method code with example usage: obj._get_field_value(field) and returns: from_cfg, self