map (function, iterable, ...) Â¶ Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel.
The grey hair ârule of thumbâ is that by the age of 50, half of the population have lost the colour in 50% of their hair. When researchers tested this rule, they found that 74% of people aged between 45 and 65 had grey hair, with an average intensity of 27%.Generally, men have more grey hair than women.he grey hair ârule of thumbâ is that by the age of 50, half of the population have lost the colour in 50% of their hair. When researchers tested this rule, they found that 74% of people aged between 45 and 65 had grey hair, with an average intensity of 27%. Generally, men have more grey hair than women.
Towards the end of this resting (telogen) phase, the hair is shed and the follicle remains empty until the anagen phase of the cycle restarts. Pigment production also turns on and off in rhythm with the hair cycle. When pigment cells turn off at the end of one hair cycle and fail to turn back on with the onset of the next, hair becomes grey. Genetic factors appear to be important in determining when we turn grey.