How does the expression of anger a toddler achieve autonomy? what functions might the expression of anger serve in later stages of development?

When a toddler is throwing a fit, he or she is trying very hard to display anger.  The child may scream, cry or both.  But while the toddler is screaming, some may view the act as annoying or useless.  But it could in fact help them to form their outbursts of sound into proper words.  

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