See Nutshell win rate by lead source for any period

**Objective:** Report how leads closed between {from-date} and {to-date} split by outcome and source.

**Step 1: Pull closed leads**

Call 
utshell-get-lead with closed-time.from set to {from-date} and closed-time.to set to {to-date}. Look at the status values that come back and treat the won value and the lost or cancelled values separately; state which values you used.

**Step 2: Resolve sources**

Call 
utshell-get-source to list the sources and channels. Match each lead to its source using the source field the lead returns. If the lead data carries no source, say so and group by company instead.

**Step 3: Report**

A table by source: leads won, leads lost, win rate, total won value and average won value. Then total won and lost. Finish with the best and worst source by win rate, ignoring sources with fewer than 3 closed leads.

**Rules & Guidelines:**

* Do not call any write tool: 
utshell-add-company, 
utshell-add-person, 
utshell-add-lead, 
utshell-add-activity, 
utshell-update-company, 
utshell-update-person, 
utshell-update-lead, 
utshell-delete-company, 
utshell-delete-person or 
utshell-delete-lead. This prompt only reads.
* Do not estimate missing values. Show them as unknown.

**Validation:**

* If either date is missing or from-date is after to-date, ask for correct dates and stop.
* If no leads closed in the range, say so.