Example-Python-Client.md

+```python
+#!/usr/bin/env python
+
+import sys
+import urllib
+import urllib2
+import json
+import time
+
+class EnsemblRestClient(object):
+    def __init__(self, server='http://rest.ensembl.org', reqs_per_sec=15):
+        self.server = server
+        self.reqs_per_sec = reqs_per_sec
+        self.req_count = 0
+        self.last_req = 0
+
+    def perform_rest_action(self, endpoint, hdrs=None, params=None):
+        if hdrs is None:
+            hdrs = {}
+
+        if 'Content-Type' not in hdrs:
+            hdrs['Content-Type'] = 'application/json'
+
+        if params:
+            endpoint += '?' + urllib.urlencode(params)
+
+        data = None
+
+        # check if we need to rate limit ourselves
+        if self.req_count >= self.reqs_per_sec:
+            delta = time.time() - self.last_req
+            if delta < 1:
+                time.sleep(1 - delta)
+            self.last_req = time.time()
+            self.req_count = 0
+        
+        try:
+            request = urllib2.Request(self.server + endpoint, headers=hdrs)
+            response = urllib2.urlopen(request)
+            content = response.read()
+            if content:
+                data = json.loads(content)
+            self.req_count += 1
+
+        except urllib2.HTTPError, e:
+            # check if we are being rate limited by the server
+            if e.code == 429:
+                if 'Retry-After' in e.headers:
+                    retry = e.headers['Retry-After']
+                    time.sleep(float(retry))
+                    self.perform_rest_action(endpoint, hdrs, params)
+            else:
+                sys.stderr.write('Request failed for {0}: Status code: {1.code} Reason: {1.reason}\n'.format(endpoint, e))
+           
+        return data
+
+    def get_variants(self, species, symbol):
+        genes = self.perform_rest_action(
+            '/xrefs/symbol/{0}/{1}'.format(species, symbol), 
+            params={'object_type': 'gene'}
+        )
+        if genes:
+            stable_id = genes[0]['id']
+            variants = self.perform_rest_action(
+                '/feature/id/{0}'.format(stable_id),
+                params={'feature': 'variation'}
+            )
+            return variants
+        return None
+
+
+def run(species, symbol):
+    client = EnsemblRestClient()
+    variants = client.get_variants(species, symbol)
+    if variants:
+        for v in variants:
+            print '{seq_region_name}:{start}-{end}:{strand} ==> {ID} ({consequence_type})'.format(**v);
+
+if __name__ == '__main__':
+    if len(sys.argv) == 3:
+        species, symbol = sys.argv[1:]
+    else:
+        species, symbol = 'human', 'BRAF'
+
+    run(species, symbol)
+```
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