track comment scraping system created, rest_api exercise tweaked

python/grep/README.md

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+# Grep
+
+Search a file for lines matching a regular expression pattern. Return the line
+number and contents of each matching line.
+
+The Unix [`grep`](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html) command can be used to search for lines in one or more files
+that match a user-provided search query (known as the *pattern*).
+
+The `grep` command takes three arguments:
+
+1. The pattern used to match lines in a file.
+2. Zero or more flags to customize the matching behavior.
+3. One or more files in which to search for matching lines.
+
+Your task is to implement the `grep` function, which should read the contents
+of the specified files, find the lines that match the specified pattern
+and then output those lines as a single string. Note that the lines should
+be output in the order in which they were found, with the first matching line
+in the first file being output first.
+
+As an example, suppose there is a file named "input.txt" with the following contents:
+
+```text
+hello
+world
+hello again
+```
+
+If we were to call `grep "hello" input.txt`, the returned string should be:
+
+```text
+hello
+hello again
+```
+
+### Flags
+
+As said earlier, the `grep` command should also support the following flags:
+
+- `-n` Print the line numbers of each matching line.
+- `-l` Print only the names of files that contain at least one matching line.
+- `-i` Match line using a case-insensitive comparison.
+- `-v` Invert the program -- collect all lines that fail to match the pattern.
+- `-x` Only match entire lines, instead of lines that contain a match.
+
+If we run `grep -n "hello" input.txt`, the `-n` flag will require the matching
+lines to be prefixed with its line number:
+
+```text
+1:hello
+3:hello again
+```
+
+And if we run `grep -i "HELLO" input.txt`, we'll do a case-insensitive match,
+and the output will be:
+
+```text
+hello
+hello again
+```
+
+The `grep` command should support multiple flags at once.
+
+For example, running `grep -l -v "hello" file1.txt file2.txt` should
+print the names of files that do not contain the string "hello".
+
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you should write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+## Running the tests
+
+To run the tests, run the appropriate command below ([why they are different](https://github.com/pytest-dev/pytest/issues/1629#issue-161422224)):
+
+- Python 2.7: `py.test grep_test.py`
+- Python 3.4+: `pytest grep_test.py`
+
+Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
+`python -m pytest grep_test.py`
+
+### Common `pytest` options
+
+- `-v` : enable verbose output
+- `-x` : stop running tests on first failure
+- `--ff` : run failures from previous test before running other test cases
+
+For other options, see `python -m pytest -h`
+
+## Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/grep` directory.
+
+You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
+
+For more detailed information about running tests, code style and linting,
+please see [Running the Tests](http://exercism.io/tracks/python/tests).
+
+## Source
+
+Conversation with Nate Foster. [http://www.cs.cornell.edu/Courses/cs3110/2014sp/hw/0/ps0.pdf](http://www.cs.cornell.edu/Courses/cs3110/2014sp/hw/0/ps0.pdf)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.