multiport docs

md/5_writing_ops/dev_creating_ports/dev_multi_ports/dev_multi_ports.md

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+# MultiPorts
+
+Ports that can have a user defined number of sub ports.
+
+`op.inMultiPort("Numbers", CABLES.OP_PORT_TYPE_NUMBER)`
+
+
+## Example
+
+This op can have multiple connections ior manually set number of ports. The output will be the sum of all those number ports.
+
+```javascript
+
+const
+    nums=op.inMultiPort("Numbers", CABLES.OP_PORT_TYPE_NUMBER),
+    outSum=op.outNumber("Sum");
+
+nums.onChange= () =>
+{
+    let n=0;
+    for(let i=0;i<nums.ports.length;i++)
+    {
+        n+=nums.ports[i].get();
+    }
+
+    outSum.set(n);
+};
+
+```
+