code: def _set_tmin(ft_struct):
      """Set the start time before the event in evoked data if possible."""
      times = ft_struct["time"]
      time_check = all(
          times[i][0] == times[i - 1][0] for i, x in enumerate(times)
      )
      if time_check:
          tmin = times[0][0]
      else:
          raise RuntimeError(
              "Loading data with non-uniform "
              "times per epoch is not supported"
          )
      return tmin
  
file_path: mne-python/mne/io/fieldtrip/utils.py
imports: import numpy
  from ..._fiff._digitization import DigPoint, _ensure_fiducials_head
  from ..._fiff.constants import FIFF
  from ..._fiff.meas_info import create_info
  from ..._fiff.pick import pick_info
  from ...transforms import rotation3d_align_z_axis
  from ...utils import _check_pandas_installed, warn
label_desc: Use image node_id 6 for calling a global function with example usage: _set_tmin(ft_struct) and returns: tmin