Name error : 'name' is not defined

I have written a short program that creates a dictionary with the number of each letter in a text file. Thanks to your help here, I am quite happy with the result.

I keep however having one irritating error.

The code below should perform the letter counter for a given language, but it gives the message:
NameError: name ‘dutch’ is not defined.
What I try to do is put the language in the function argument and then look for the file that has the name language.txt and run the program on it.
I asusme that this is again an issue with python no accepting a string as part of a file path, but I have tried several ways to work around it, with no effect.

The program works when I enter ‘dutch.txt’ as argument, but I would prefer to just be able to enter the language as argument.

This is the code:

Dit programma maakt een dictionary van een gegeven tekst met daarin per letter het getelde aantal

import os
from pathlib import Path

languages = ["dutch", "english", "french", "german", "italian", "spanish"]

source_dir = Path('C:/Users/gwovi/PycharmProjects/VickyGwosdz_LanguageDetector')
files = source_dir.glob('*.txt')

# Function that creates a dictionary with number of each letter
def letterfrequency(input_tekst):
    d = dict()  # maak een nieuwe dictionary voor de te tellen file
    for letter in input_tekst:  # als de letter al in de dict voorkomt, tel er 1 bij, anders zet teller op 1
        if letter in d:
            d[letter] += 1
            d[letter] = 1
    return d

# Combine all txt file per language in one large input file
for file in os.listdir(source_dir):
    if file.endswith(".txt"):
        i = 0
        # Iterate through the list of languages
        for i in range(len(languages)):
            language = languages[i]
            if language in file:
                # Per language in the list, open every file, read and close
                # Write contents of the file to a new txt file consecutively
                with open(file, 'r', encoding='utf-8') as f2:
                    input_txt =
                with open(language + '.txt', 'a+', encoding='utf-8') as f3:
        i += 1

# Analyse requested language
def languagefrequencycounter(taal):
    tetellentaal = taal.read_text(encoding='utf_8')
    no_space_taal = tetellentaal.replace(" ", "")  # Remove all spaces
    getelde_taal = letterfrequency(no_space_taal)
    with open(taal + '-geteld.txt', 'w', encoding='utf-8') as f4:


dutch is not a variable named defined in your program. Try "dutch" instead, as in