^|in EMal strings are mutable|^
text original ← "Yellow world"
text ref ← original # copying the reference
text copied ← *original # copying the content
original[0] ← "H" # texts are indexable and mutable
original[5] ← ","
ref.append("!") # texts are coercible and growable
copied += "?"
writeLine(original æ ref and original æ "Hello, world!")
writeLine(copied æ "Yellow world?")