code: def get_linestyle(self, increment=1):
          
  
          i = self.linestyles_index
  
          self.linestyles_index += increment
          if self.linestyles_index >= len(self.linestyles):
              self.linestyles_index = self.linestyles_index-len(self.linestyles)
              if self.linestyles_index >= len(self.linestyles): self.linestyles_index=0 # to be safe
  
          return self.linestyles[i]
docs: Returns the current marker, then increments the marker by what's specified