docs: def style_chg_label(self,type,symb=None,edc=None,fac=None,smbsz=None,edw=None,lab=None):
          '''
          This routine changes the plotting style that is set by default.
          The style is changed according the the label that you choose.
          Changing according to reference, use style_chg_ref() function!
          You can change it back to default by resetting the filter using
          g.reset_filter() routine, assuming that g is your instance. The
          format that is used here is:
  
          ['Symbol', 'Edge color', 'Face color', 'Symbol size', 'Edge width'
          ,'Label']
  
          You can see the current styles by running
  
          Attention: You have to give values to all variables that are
          compatible with the python mathplotlib. If not, it's your fault
          if nothing works.
  
          g.style
  
          Parameters
          ----------
          type : string
              Select the label of the grains you want to change.
          symb : string, optional
              Select new symbol. None for no change.
          edc : string, optional
              Select new edge color. None for no change.
          fac : string, optional
              Select new face color. None for no change.
          smbsz : string, optional
              Select new symbol size. None for no change.
          edw : string, optional
              Select new edge width. None for no change.
          lab : string, optional
              Select new label. None for no change. Watch out, if you
              want to do more specifications later, the type will
              have changed to the new label.
          '''
  
          # do stuff for selected type
          for i in range(len(self.style)):
              # check if type is correct, otherwise continue directly
              if self.style[i][self.styledict['Label']] == type:
                  # change symbol:
                  if symb != None:
                      self.style[i][self.styledict['Symbol']] = symb
                  # change edge color
                  if edc != None:
                      self.style[i][self.styledict['Edge color']] = edc
                  # change face color
                  if fac != None:
                      self.style[i][self.styledict['Face color']] = fac
                  # change symbol size
                  if smbsz != None:
                      self.style[i][self.styledict['Symbol size']] = smbsz
                  # change edge width
                  if edw != None:
                      self.style[i][self.styledict['Edge width']] = edw
                  # change label
                  if lab != None:
                      self.style[i][self.styledict['Label']] = lab