blocktrail / blocktrail-sdk-php

            $change = $this->determineChange($utxos, $send, $fee);

            // if change is not dust we need to add a change output

            if ($change > Blocktrail::DUST) {

                $send[] = ['address' => 'change', 'value' => $change];

            } else {

                // if change is dust we do nothing (implicitly it's added to the fee)

                $change = 0;

            }

        } else {

            $fee = $this->determineFee($utxos, $send, $txBuilder->getFeeStrategy(), $optimalFeePerKB, $lowPriorityFeePerKB);

                    $change = $this->determineChange($utxos, $send, $fee2);

                    // if change is not dust we need to add a change output

                    if ($change > Blocktrail::DUST) {

                        $send[$changeIdx] = ['address' => 'change', 'value' => $change];

                    } else {

                        // if change is dust we do nothing (implicitly it's added to the fee)

                        $change = 0;

                    }

                }

            }

        }