This function will help you to modify the flow of the survey for the respondent by apply branching logic via velocity script.
$survey.branchTo("Question Code")
Consider a scenario where you want to alter the flow of the survey based on the answer options selected in Q1 of the survey. If respondent select answer option 1 in Q1 then redirect to Q3 and if answer option 2 is selected redirect the user to Q4 and so on.
# if (${Q1} == 1 )
$survey.branchTo("Q3")
# end
# if (${Q1} == 2)
$survey.branchTo("Q4")
# end
# if (${Q1} == 3)
$survey.branchTo("Q5")
# end
# if (${Q1} == 4)
$survey.branchTo("Q6")
# end