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+Removes the specified entries from a stream, and returns the number of entries
+deleted.  This number may be less than the number of IDs passed to the command in
+the case where some of the specified IDs do not exist in the stream.
+
+Normally you may think at a Redis stream as an append-only data structure,
+however Redis streams are represented in memory, so we are also able to 
+delete entries. This may be useful, for instance, in order to comply with
+certain privacy policies.
+
+## Understanding the low level details of entries deletion
+
+Redis streams are represented in a way that makes them memory efficient:
+a radix tree is used in order to index macro-nodes that pack linearly tens
+of stream entries. Normally what happens when you delete an entry from a stream
+is that the entry is not *really* evicted, it just gets marked as deleted.
+
+Eventually if all the entries in a macro-node are marked as deleted, the whole
+node is destroyed and the memory reclaimed. This means that if you delete
+a large amount of entries from a stream, for instance more than 50% of the
+entries appended to the stream, the memory usage per entry may increment, since
+what happens is that the stream will become fragmented. However the stream
+performance will remain the same.
+
+In future versions of Redis it is possible that we'll trigger a node garbage
+collection in case a given macro-node reaches a given amount of deleted
+entries. Currently with the usage we anticipate for this data structure, it is
+not a good idea to add such complexity.
+
+@return
+
+@integer-reply: the number of entries actually deleted.
+
+@examples
+
+```
+> XADD mystream * a 1
+1538561698944-0
+> XADD mystream * b 2
+1538561700640-0
+> XADD mystream * c 3
+1538561701744-0
+> XDEL mystream 1538561700640-0
+(integer) 1
+127.0.0.1:6379> XRANGE mystream - +
+1) 1) 1538561698944-0
+   2) 1) "a"
+      2) "1"
+2) 1) 1538561701744-0
+   2) 1) "c"
+      2) "3"
+```