docs: def charge_series(seq, granularity=0.1):
      """Calculates the charge for pH 1-13.
  
      Parameters
      ----------
      seq : str
          Sequence of amino acids.
      granularity : float, optional
          Granularity of pH values i.e. if 0.1 pH = [1.0, 1.1, 1.2...]
      """
      if 'X' in seq:
          warnings.warn(_nc_warning_str, NoncanonicalWarning)
      ph_range = numpy.arange(1, 13, granularity)
      charge_at_ph = [sequence_charge(seq, ph) for ph in ph_range]
      return ph_range, charge_at_ph