Conditional from function

is_field() {
	local field
	for field in $FIELDS; do
		if [[ "$field"  == "$1" ]]; then
			return 0
		fi
	done
	return 1
}

if is_field; then
  ...
fi

List

TRAILERS=()
TRAILERS+=( "--trailer" "Co-authored-by: $(get_author_name) <$(get_author_email)>")
git commit "$@" "${TRAILERS[@]}"

Loop over multiline variable

LINES=$(cat <<EOF
line1
line2
EOF
)

while IFS='\n' read line; do
  ...
done <<< "$LINES"