copy (2)

print-it: func [/local str] [
    str: ""
    insert str "ha"
    print str
]

print-it
ha
print-it
haha
print-it
hahaha

When initializing a string or block series, use copy on the value to make is a unique series. In this example, because copy wasn’t used, the empty string series is modified with every call of print-it.

print-it: func [/local str] [
    str: copy ""
    insert str "ha"
    print str
]

print-it
ha
print-it
ha
print-it
ha