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# count

Returns an observable sequence containing a value that represents how many elements in the specified observable sequence satisfy a condition if provided, else the count of items.

## Arguments

1. `[predicate]` *(`Function`)*: A function to test each element for a condition.  The callback is called with the following information:
   1. the value of the element
   2. the index of the element
   3. the Observable object being subscribed
2. `[thisArg]` *(`Any`)*: Object to use as `this` when executing `predicate`.

## Returns

*(`Observable`)*: An observable sequence containing a single element with a number that represents how many elements in the input sequence satisfy the condition in the predicate function if provided, else the count of items in the sequence.

## Example

### Without a predicate

### With a predicate


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