def _resolve_credential(self, credential):
if self._credentials_found_in_instance:<EOL><INDENT>return<EOL><DEDENT>elif self._credentials_found_in_envars():<EOL><INDENT>return os.getenv('<STR_LIT>' + credential.upper())<EOL><DEDENT>else:<EOL><INDENT>return self.storage.fetch_credential(<EOL>credential=credential, profile=self.profile)<EOL><DEDENT>
Resolve credential from envars or credentials store.

        Args:
            credential (str): Credential to resolve.

        Returns:
            str or None: Resolved credential or ``None``.