pylint: Resolve consider-using-enumerate

Use enumerate instead of iterating with range and len.
This pylint message is emitted when code that iterates with range and
len is encountered. Such code can be simplified by using the enumerate
built-in. [1]

In addition, remove some unused variables to avoid warnings
`unused-argument` and `redefined-variable-type`.

[1] https://pylint.readthedocs.io/en/latest/technical_reference/features.html#id23

Signed-off-by: Radostin Stoyanov <rstoyanov1@gmail.com>

virtManager/graphwidgets.py

@@ -29,14 +29,11 @@ def rect_print(name, rect):
           (name, rect.height, rect.width, rect.x, rect.y))
 
 
-def _line_helper(cairo_ct, x, y, w, h, points, for_fill=False):
-    ignore = w
-    bottom_baseline = y + h
+def _line_helper(cairo_ct, bottom_baseline, points, for_fill=False):
     last_was_zero = False
     last_point = None
 
-    for index in range(0, len(points)):
-        x, y = points[index]
+    for index, (x, y) in enumerate(points):
 
         # If stats value == 0, we don't want to draw a line
         is_zero = bool(y == bottom_baseline)
@@ -65,11 +62,11 @@ def _line_helper(cairo_ct, x, y, w, h, points, for_fill=False):
     return last_point
 
 
-def draw_line(cairo_ct, x, y, w, h, points):
+def draw_line(cairo_ct, y, h, points):
     if not len(points):
         return
 
-    last_point = _line_helper(cairo_ct, x, y, w, h, points)
+    last_point = _line_helper(cairo_ct, y + h, points)
     if not last_point:
         # Nothing to draw
         return
@@ -82,7 +79,7 @@ def draw_fill(cairo_ct, x, y, w, h, points, taper=False):
     if not len(points):
         return
 
-    _line_helper(cairo_ct, x, y, w, h, points, for_fill=True)
+    _line_helper(cairo_ct, y + h, points, for_fill=True)
 
     baseline_y = h + y + 1
     if taper:
@@ -217,10 +214,7 @@ class CellRendererSparkline(Gtk.CellRenderer):
         # Set color to dark blue for the actual sparkline
         cr.set_line_width(2)
         cr.set_source_rgb(0.421875, 0.640625, 0.73046875)
-        draw_line(cr,
-                  cell_area.x, cell_area.y,
-                  cell_area.width, cell_area.height,
-                  points)
+        draw_line(cr, cell_area.y, cell_area.height, points)
 
         # Set color to light blue for the fill
         cr.set_source_rgba(0.71484375, 0.84765625, 0.89453125, .5)
@@ -369,7 +363,7 @@ class Sparkline(Gtk.DrawingArea):
             if self.num_sets == 1:
                 pass
 
-            draw_line(cr, 0, 0, w, h, points)
+            draw_line(cr, 0, h, points)
             if self.filled:
                 # Fixes a fully filled graph from having an oddly
                 # tapered in end (bug 560913). Need to figure out