Add an example to create a MIDI file

.gitignore

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 .idea/
 venv/
+.DS_Store
 
 # Byte-compiled / optimized / DLL files
 __pycache__/

CHANGELOG.md

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 ## Forthcoming
 
+- Add an example to create a MIDI file.
+
 ## v0.5.1
 
 - Add `m7b9b5` quality.

README.md

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 <Chord: E7>  # V7 of A minor
 ```
 
+## Examples
+
+- [pychord-midi.py](./examples/pychord-midi.py) - Create a MIDI file using PyChord and pretty_midi.
+
 ## Supported Python Versions
 
 - 2.7

examples/pychord-midi.py

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+# An example to create MIDI file with PyChord and pretty_midi
+# Prerequisite: pip install pretty_midi
+# pretty_midi: https://github.com/craffel/pretty-midi
+
+
+import pretty_midi
+
+from pychord import Chord
+
+
+def create_midi(chords):
+    midi_data = pretty_midi.PrettyMIDI()
+    piano_program = pretty_midi.instrument_name_to_program('Acoustic Grand Piano')
+    piano = pretty_midi.Instrument(program=piano_program)
+    length = 1
+    for n, chord in enumerate(chords):
+        for note_name in chord.components_with_pitch(root_pitch=4):
+            note_number = pretty_midi.note_name_to_number(note_name)
+            note = pretty_midi.Note(velocity=100, pitch=note_number, start=n * length, end=(n + 1) * length)
+            piano.notes.append(note)
+    midi_data.instruments.append(piano)
+    midi_data.write('chord.mid')
+
+
+def main():
+    chords_str = ["C", "Dm7", "G", "C"]
+    chords = [Chord(c) for c in chords_str]
+    create_midi(chords)
+
+
+if __name__ == '__main__':
+    main()