Fix issue #8

- Added a new function loop to ask for a test the key

pdfca.py

@@ -12,6 +12,15 @@
 import PyPDF2
 
 
+def checkIndex(dataframe):
+    key = click.prompt('Please enter item to explore')
+    while True:
+        if key in dataframe.index:
+            return key
+        else:
+            key = click.prompt('Please enter a valid key')
+
+
 def count(x, term):
     search = re.findall(term.strip().lower(), x.strip().lower())
     num = len(search)
@@ -235,9 +244,10 @@ def search(term, binary, form, search_type, number):
     else:
         results = dropped.sum().sort_values(by=[term])
     click.echo(f'Top {number} results:')
-    click.echo(results.tail(number))
+    results = results.tail(number)
+    click.echo(results)
     if click.confirm('\nWould you like to drill down?'):
-        key = click.prompt('Please enter item to explore')
+        key = checkIndex(results)
         filtered = grouped.get_group(key).sort_values(by=[term])
         filtered = filtered.set_index('page')
         click.echo()