You run m independent tests, each at significance threshold alpha, and the
null is true for all of them. Return the probability of at least one false
positive somewhere in the family.
This is the number that motivates the Bonferroni correction: twenty tests at 0.05 each are more likely than not to produce a "significant" result from pure noise.
Input
alpha = 0.05
m = 20
Output
0.6415140775914581