Operator bpy.ops.font.delete.poll() failed, context is incorrect code example

Example 1: bpy.ops.object.mode_set.poll()

import bpy
import random

#for loopv in range (1000):
ctx = bpy.context.copy()
for area in bpy.context.screen.areas:
   if area.type == 'CLIP_EDITOR':
   ctx['area'] = area

bpy.ops.clip.select_all(ctx,action='DESELECT')
bpy.ops.clip.detect_features(ctx)
bpy.ops.clip.track_markers(ctx,backwards=False, sequence=False)

Example 2: bpy.ops.object.mode_set.poll()

bpy.data.movieclips["Name.png"].(null) = 0.99