Simple Multiply node for Nuke extended with parameters to control a flicker noise.

CS_Flicker.tcl

set cut_paste_input [stack 0]
version 10.5 v3
push $cut_paste_input
Multiply {
 channels rgb
 value {{"offset + (noise(frame * frequency1, seed) + noise(frame * frequency2, seed)) * 0.5 * amplitude"}}
 name CS_Flicker1
 addUserKnob {20 Flicker}
 addUserKnob {7 frequency1}
 frequency1 0.123
 addUserKnob {7 frequency2}
 frequency2 0.456
 addUserKnob {7 amplitude}
 amplitude 0.5
 addUserKnob {7 offset}
 offset 1
 addUserKnob {3 seed}
 seed 1234
}