code: def slope(signal):
      """Computes the slope of the signal.
  
      Slope is computed by fitting a linear equation to the observed data.
  
      Feature computational cost: 1
  
      Parameters
      ----------
      signal : nd-array
          Input from which linear equation is computed
  
      Returns
      -------
      float
          Slope
  
      """
      t = np.linspace(0, len(signal) - 1, len(signal))
  
      return np.polyfit(t, signal, 1)[0]
  
imports: import scipy.signal
  from tsfel.feature_extraction.features_utils import *
label_desc: Use image node_id 12 for calling a global function with example usage: slope(signal) and returns: np