class_docstr: Truncate unequal length panels to lower/upper bounds.
  
  Truncates all series in panel between lower/upper range bounds.
  
  Parameters
  ----------
  lower : int, optional (default=None) bottom range of the values to
              truncate can also be used to truncate to a specific length
              if None, will find the shortest sequence and use instead.
  upper : int, optional (default=None) upper range, only required when
              paired with lower.
              This is used to calculate the range between. exclusive.
              if None, will truncate from 0 to the lower bound.
code: def _get_min_length(X):
      def get_length(input):
          return min(map(lambda series: len(series), input))
  
      return min(map(get_length, X))
  
file_path: sktime/sktime/transformations/panel/truncation.py
imports: import numpy
  import pandas
  from sktime.transformations.base import BaseTransformer
label_desc: Use image node_id 2 for calling the TruncationTransformer obj's underlying member method code with example usage: obj._get_min_length(X) and returns: min, min