Add documentation to commands

ethereumetl/cli/extract_csv_column.py

@@ -33,7 +33,7 @@
 @click.option('-o', '--output', default='-', type=str, help='The output file. If not specified stdout is used.')
 @click.option('-c', '--column', required=True, type=str, help='The csv column name to extract.')
 def extract_csv_column(input, output, column):
-    """Extracts column from given CSV file."""
+    """Extracts column from given CSV file. Deprecated - use extract_field."""
     set_max_field_size_limit()
 
     with smart_open(input, 'r') as input_file, smart_open(output, 'w') as output_file:

ethereumetl/cli/extract_field.py

@@ -31,4 +31,5 @@
 @click.option('-o', '--output', default='-', type=str, help='The output file. If not specified stdout is used.')
 @click.option('-f', '--field', required=True, type=str, help='The field name to extract.')
 def extract_field(input, output, field):
+    """Extracts field from given CSV or JSON newline-delimited file."""
     misc_utils.extract_field(input, output, field)

ethereumetl/cli/filter_items.py

@@ -31,6 +31,7 @@
 @click.option('-p', '--predicate', required=True, type=str,
               help='Predicate in Python code e.g. "item[\'is_erc20\']".')
 def filter_items(input, output, predicate):
+    """Filters rows in given CSV or JSON newline-delimited file."""
     def evaluated_predicate(item):
         return eval(predicate, globals(), {'item': item})
     misc_utils.filter_items(input, output, evaluated_predicate)