Cannot run the example

**Describe the bug**
Now the import code in `runterm.py` works for the `monkeytype`, however, if we just want to run the program, it will show there is an import error

**To Reproduce**
Steps to reproduce the behavior:
1. Go to `example`
2. Run `pipenv run termfrequency/runtermfreq.py inputs/input.txt`
3. See error

**Expected behavior**
Expect to run and produce the output with the words and frequencies

Start in the example directory with the documented `pipenv run termfrequency/runtermfreq.py inputs/input.txt` command, then inspect the import path used by `runterm.py` and capture the reported error. Done means the example runs without the import error and produces word-frequency output for `inputs/input.txt`.

Written by the indexing model from the issue text.