code: def plotGrid(self, numLines=(5,5), lineWidth=1, colour="#777777"):
          
          x1, x2, y1, y2 = mp.axis()
          ra1, dec0 = self.pixToSky(x1, y1)
          ra0, dec1 = self.pixToSky(x2, y2)
  
          xNum, yNum = numLines
          self.raRange, self.decRange  = self.getRaDecRanges(numLines)
  
          #import pdb; pdb.set_trace()
          #Guard against Ra of zero within the plot
          a1 = np.abs(ra1-ra0)
          a2 = np.abs( min(ra0, ra1) - (max(ra0, ra1) - 360))
          if a2 < a1:     #Then we straddle 360 degrees in RA
              if ra0 < ra1:
                  ra1 -= 360
              else:
                  ra0 -= 360
  
  
          #Draw lines of constant dec
          lwr = min(ra0, ra1)
          upr = max(ra0, ra1)
          stepX = round((upr-lwr) / float(xNum))
          ra_deg = np.arange(lwr - 3*stepX, upr + 3.5*stepX, 1, dtype=np.float)
          for dec in self.decRange:
              self.plotLine(ra_deg, dec, '-', color = colour, linewidth = lineWidth)
  
  
          #Draw lines of const ra
          lwr = min(dec0, dec1)
          upr = max(dec0, dec1)
          stepY = round((upr-lwr) / float(yNum))
          dec_deg = np.arange(dec0 - 3*stepY, dec1 + 3.5*stepY, 1, dtype=np.float)
          for ra in self.raRange:
              self.plotLine(ra, dec_deg, '-', color = colour, linewidth = lineWidth)
  
          mp.axis([x1, x2, y1, y2])
docs: Plot NUMLINES[0] vertical gridlines and NUMLINES[1] horizontal gridlines,
          while keeping the initial axes bounds that were present upon its calling.
          Will not work for certain cases.