s1 = "string"
s2 = "str"
s3 = "ing"
s4 = "xyz"

println["$s1 starts with $s2: " + startsWith[s1, s2]]
println["$s1 starts with $s4: " + startsWith[s1, s4]]
println["$s1 ends with $s3: " + endsWith[s1, s3]]
println["$s1 ends with $s4: " + endsWith[s1, s4]]
position[s1, s2]
position[s1, s4]

position[s1, s2] :=
{
   pos = indexOf[s1,s2]
   if pos == -1
      println["$s1 does not contain $s2"]
   else
      println["$s1 contains $s2 at position $pos"]
}