input: Write a python function to get the metadata for a given neuron using its neuron name.
  assert metadata('mb100318-a') == {'Archive name': 'Scanziani', 'Submitter': 'Michael Scanziani', 'Cell type': 'Interneuron', 'Region': 'Somatosensory cortex', 'Species': 'Mus musculus', 'Original Format': 'NMO', 'Morphological characteristics': 'Aspiny', 'Morphological format': 'Standardized', 'Neuron Reconstruction': 'Yes', 'Staining method': 'biocytin'}
  assert metadata('some_neuron_name') == {'key1': 'value1', 'key2': 'value2'}
output: def metadata(neuron_name):
      neuron_metadata = {
          'mb100318-a': {
              'Archive name': 'Scanziani',
              'Submitter': 'Michael Scanziani',
              'Cell type': 'Interneuron',
              'Region': 'Somatosensory cortex',
              'Species': 'Mus musculus',
              'Original Format': 'NMO',
              'Morphological characteristics': 'Aspiny',
              'Morphological format': 'Standardized',
              'Neuron Reconstruction': 'Yes',
              'Staining method': 'biocytin'
          },
          'some_neuron_name': {
              'key1': 'value1',
              'key2': 'value2'
          }
      }
      return neuron_metadata.get(neuron_name, {})