def process(FILE_IN):
    # Read file.
    lines_in = []
    with open(FILE_IN) as file:
        for line in file:
            lines_in.append(line.rstrip())

    # Translate.
    lines_out = []

    isDeclaration = False
    isDeclarationLine = False
    isBody = False
    functionName = None
    returnType = None
    argumentNames = []
    argumentTypes = []

    for ln in lines_in:
        ln = ln.rstrip()

        # Ignore includes.
        if "#include" in ln:
            continue

        parts = ln.split(" ")
        count = len(parts)
        lastPart = parts[count - 1]
        if not isBody and lastPart.endswith("("):
            isDeclaration = True
            isDeclarationLine = True
            isBody = False

        # End of function arguments.
        if not isDeclarationLine and not isBody and ln.endswith(") {"):
            isDeclaration = False
            isBody = True

        # Function argument.
        if (
            isDeclaration and
            not isDeclarationLine and
            not isBody and
            not ln.endswith(") {")
        ):
              print(f"TODO argument: '{ln}'")

        # Function return type and function name.
        if isDeclaration and lastPart.endswith("("):
            functionName = lastPart[:-1]
            returnType = ln[:-len(lastPart) - 1] # -1 for space before function name
            print(f"Function name: '{functionName}'")
            print(f"Return type: '{returnType}'")
            isDeclarationLine = False

        lines_out.append(ln)

    return "\n".join(lines_out)