lowercase words that start with "a" (hint: use [a-z] for any lowercase letter)

should match: apples | almonds | apricots | avocados |
should not match: barley | berkeley | aTestStringWithCaps |

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lowercase words with at least two "a"s

should match: aardvark | avocados | parallel |
should not match:  almonds | apricots | caller |

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lowercase words with at least two "a"s, but "a"s don't start or end the word

should match: | parallel | calendar |
should not match: almonds | alabaster | caller | aardvark | avocados | bandana

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lowercase words with at least two occurances of letters from the set {"a", "b", "c"}

should match: barley | avocados | tabby | back | apricots 
should not match: bitter | almonds | oboe |

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alternating sequences of "a" and "b" 

should match: ababa | babab | abab | baba | b | a | ba |
should not match: bbaabbaa | aabab | bbaba | bb | aa | 

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email addresses (hint: [A-Z] for any uppercase letter)

should match: hello@hello.com | wowfunactivity@a.b | testWithCaps@gmail.com 
should not match: test@test@test.com | www.google.com | thisisjustastring 

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any number of "a"s followed by the same number of "b"s

should match: aaabbb | ab | aaaaabbbbb | aaabbb |
should not match: abb | aaab | aaaaabb |



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spoiler:
last task can't be done!