# OCR Numbers

Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is
represented, or whether it is garbled.

# Step One

To begin with, convert a simple binary font to a string containing 0 or 1.

The binary font uses pipes and underscores, four rows high and three columns wide.

```text
     _   #
    | |  # zero.
    |_|  #
         # the fourth row is always blank
```

Is converted to "0"

```text
         #
      |  # one.
      |  #
         # (blank fourth row)
```

Is converted to "1"

If the input is the correct size, but not recognizable, your program should return '?'

If the input is the incorrect size, your program should return an error.

# Step Two

Update your program to recognize multi-character binary strings, replacing garbled numbers with ?

# Step Three

Update your program to recognize all numbers 0 through 9, both individually and as part of a larger string.

```text
 _ 
 _|
|_ 
   
```

Is converted to "2"

```text
      _  _     _  _  _  _  _  _  #
    | _| _||_||_ |_   ||_||_|| | # decimal numbers.
    ||_  _|  | _||_|  ||_| _||_| #
                                 # fourth line is always blank
```

Is converted to "1234567890"

# Step Four

Update your program to handle multiple numbers, one per line. When converting several lines, join the lines with commas.

```text
    _  _ 
  | _| _|
  ||_  _|
         
    _  _ 
|_||_ |_ 
  | _||_|
         
 _  _  _ 
  ||_||_|
  ||_| _|
         
```

Is converted to "123,456,789"

## 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 shold write:

```python
raise Exception("Meaningful message indicating the source of the error")
```


## Submitting Exercises

Note that, when trying to submit an exercise, make sure the solution is in the `exercism/python/<exerciseName>` directory.

For example, if you're submitting `bob.py` for the Bob exercise, the submit command would be something like `exercism submit <path_to_exercism_dir>/python/bob/bob.py`.

For more detailed information about running tests, code style and linting,
please see the [help page](http://exercism.io/languages/python).

## Source

Inspired by the Bank OCR kata [http://codingdojo.org/cgi-bin/wiki.pl?KataBankOCR](http://codingdojo.org/cgi-bin/wiki.pl?KataBankOCR)

## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.