How many σ and π bonds are present in a molecule of cumulene?

A hydrocarbon with three or more consecutive (cumulative) double bonds is known as a cumulene. They are analogous to allenes, only exhibiting a more elongated chain. The basic molecule in this category is butatriene, which is also simply known as cumulene.  

In the structure of a cumulene, there are 3 double bonds and 4 single bonds. The double bond comprises 1 sigma bond, and 1 pi bond and 4 hydrogen bond produces a sigma bond with carbon. Thus, the molecule of cumulene comprises 7 sigma bonds and 3 pi bonds.  

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it is the most commonly accepted one